Sterilizer



March 30, 1954 R. L. JEWELL ETAL I 2,673,379

STERILIZER Filed Aug. 10, 1950, 2 Sheets-Sheet l March 30, 1954 R JEwgLL ET AL A 2,673,379

STERILIZER Filed Aug. 10, 1950 2 Sheets-Sheet 2 Patented Mar. 30, 1954 STERILIZER Raymond L. Jewell and George J. Dyckes, Erie, Pa., assignors to American Sterilizer Company, Erie, Pa., a corporation of Pennsylvania Application August 10, 1950, Serial No. 178,716

3 Claims.

Sterilizers have been made in which a body of Water is heated by injected steam. A detergent may be added to the water so that the sterilizer both washes and sterilizes. This invention is intended to improve the operation of such sterilizers by injecting air during the heating up period. This is contrary to the usual sterilizer practice where provisions are made for the elimination of air rather than for the injection of air. Air injection decreases the noise of operation caused by the sudden condensation of the steam. The air injection also improves the washing action of the detergent by creating more suds. Further objects and advantages appear in the specification and claims.

In the drawings, Fig. 1 is a section through a non-pressure sterilizer; Fig. 2 is an enlarged section through the steam and air injector; and Fig. 3 is a section through a pressure type sterilizer.

In the non-pressure type of sterilizer shown in Figure 1 there is a tank I having amanually controlled drain valve 2 leading to a drain line 3 and having an overflow 4 to the drain line which maintains the desired water level 5 within the tank. The tank has a loose fitting cover 6 which prevents pressures above atmospheric within the tank. The parts so far described are or may be of conventional construction. Such sterilizers are usually used for instruments which are placed on racks or trays (not shown) and immersed in the water.

On the bottom wall of the tank is a steam injector having a base I threaded to receive a steam line 8 and air line 9. On the top of the base 1 is secured a circular baffle it) having its center portion H spaced slightly above the outlet of the steam line 8. Surrounding the steam line there is an annular recess I 2 having its outer upper surface covered by a disc baflie l3. The air line 9 leads into the annular recess. The baffie [3 has a central opening I4 slightly spaced from the outer surface of a boss I5 so as to provide an annular passageway leading from the recess to the space between the bafiles l3 and It. The top of the boss l5 cooperates with the depressed central portion of the baffle 0 to provide an annular steam ejection nozzle discharging steam uniformly in all directions around the steam inlet pipe 8. The upper surface of the bafile I 3 is below the upper surface of the boss I5 so that there is a step or a sudden enlargement or increase in cross section at point It where the steam flows past the opening to the air chamber l2. This sudden enlargement produces an injector action which sucks air from the chamber [2 and entrains the air in the jet of steam. The steam jet with the entrained air flows radially outward in all directions to the flaring passage between the baffles 10 and I3 and is discharged radially through the peripheral passageway H. As the steam and air flow along the undersurface of thebaflle, water is drawn in through perforated openings l8 and is mixed with the radially discharged jet of air and steam. During the initial stages of the operation of the sterilizer when the water is cool, there is .a sudden condensation of the steam as it contacts the water. This sudden condensation, in the absence of air, would produce a crackling noise due to the sudden collapse of the steam bubbles. However the mixture of air and steam provides an air cushion which reduces the noise. As the water comes up to temperature, the noise disappears due to the slowness with which the steam bubbles condense.

The injection of air is due to the velocity of the steam discharge. At the start of the sterilizing operation, the steam flows at the maximum rate through a thermostatically controlled valve is having a thermostatic bulb 20 located in the upper part of the sterilizer tank I above the water level 5. When the water in the tank becomes heated, there is steam above the water level 5 which heats the thermostat bulb 20 and shuts the valve l9 against an adjustable'stop 2| which reduces the steam flow to a value at which there is noiniection of air but nevertheless there is a sufiicient flow of steam to maintain the temperature within the tank at 212 F. The air line 9 has its intake 22 substantially above the water line 5 and preferably connected to the interior of the tank I. When the steam flow is reduced by the thermostatic valve l9. there accordingly can be no further injection of air. At the same time because the inlet .22 to the air line is above the water levelj5, there canbe no leakage of water through the air line.

By this arrangement there is an injection. of air into the sterilizer during the heating up period when no sterilizing. is taking place. As soon as the sterilizer comes up to temperature,- the injection of. air, which. would be. disadvantageous due to the possibility of air born contamination, is stoppedby the reduction in the flow of steam into the.,sterilizer. While the thermostatic valve l9. automatically cuts-down the flow of steam at the right time, it would be possible to substitute a manual control for the, steam supply.

In the use of thesterilizer the tank is filled to the desired water level 5 and. the articles to be sterilized are immersed in the water. The steam supply is then turned 'on by a suitable manual control valve, not shown, and the steam flows into the injector. at the maximum rate... Untilthe sterilizer is heated to sterilizing temperature, the flow of steam causes an injection of air through the line 9.. ..0f.co'use,.;. as the sterilizer comes up to temperature, the air contains a progressively greater proportion of steam and when up to temperature, the atmosphere is almost wholly steam; IEhe inlet to this line 22 is connected to-the upper. part of the tank but since the cover 6 fits loosely there is a possibility of drawing some air in from the outside air. The steam jet discharged radially through the passageway I1 sets up a circulation within the tank indicated by the arrow 23 which insures uniform heating of the water. The overflow 4 prevents increase of the water level 5 duev tocondensate. When the sterilizer comes up to temperature, the thermostatic bulb is heated and operates the thermostatic valve I9 to close the valve against the adjustable stop 2| which reduces the flow of. steam tothat required to maintain the sterilizer at;2l2 F. At this lower rate, there is no injection of. air through. the air line 9 and accordingly there isno danger of contamination. The injection of air is accordingly terminated at the start of. the sterilizing, operation which be- .gins when the sterilizer is up to temperature.

Prior to this time, there is no substantial sterilizing. and the injection of air is not harmful to the sterilizing. operation and does have the positive. advantage of substantially reducing the noise of operation.

In Fig. 3 there is shown a pressure type sterilizer such as is used for the combined sterilizing and washing of surgical instruments. A sterilizer has tank 24 provided at its upper part with a. door through which the instruments are loaded. and unloaded. In the lower part of the tank. there is a baflie 25a. which divides the lower part of the tank into a. liquid chamber 26 and an. overflow 21 leading to a drain line 28 through a steam trap 29.. Thereis also. provided suitable mechanism for raising and lowering. the instruments (not shown)- This mechanism raises the instruments up to levelof the door 25- and above the surface of the water to permit loading and unloading and drops the instruments into the water during sterilizing. The parts so far described are or may be of conventional construction, At the lower part. of the tank. 24 there is a steam injector of. the same construction illustrated in Figures 1 and 2 corresponding parts of which are identified by the same reference numerals. The steam injector is connected to a steam line 8 controlled. by a pressure control valve l9a responsive to steam pressure in the chamber which corresponds to the temperature. The steam injector is also connected to an air line 9 having its inlet 22 at the upper part of the tank 24 above the water level. Thesteam pressure tube 20a controlling the valve l9a is likewise located in the upper part of the sterilizer tank 24.

In the use of the sterilizer, the water chamber 26 is filled with water, the instruments with the required amount of detergent are loaded through the door 25 and immersed in the water, the door 25' is locked closed and the steam is turned on in the line 8 by means of a manual valve (not shown). As in the previously described construction there is a radial discharge of a jet of air, steam and water through the passageway I 7. This discharge sets up a violent agitation of water around the immersed instruments. In this arrangement, not only does the air out down noise of operation while the water is heating up, but the air also improves the washing action by increasing the formation of suds which dislodge the foreign matter from the instruments and float it out over the overflow 21. The injection of air continues until the sterilizer is heated to sterilizing temperature and corresponding steam pressure. Steam. pressure is maintained by the control valve. 19a while. the remaining air and overflow is discharged through trap 29. In this sterilizer, it will be noted that the air injection stops as soon as the sterilizer comes up to temperature and pressure. In this sterilizer, however, the air which is injected is that initially contained within the sterilizer. As the sterilizer comes. up to temperature, the amount of air within the sterilizer is decreased as the steam generated displaces the air and forces it out through. the steam trap 22. At the conclusion of the sterilizing operation, the water chamber 26 is drained through a suitable drain valve (not shown) the instruments are elevated to a level opposite the door 25, and unloaded through the door.

What we claim as new is:

1. In a sterilizer, a tank having a water chamber in its lower part in which articles to be sterilized. are immersed, an overflow maintaining the water level in the chamber, a closure for the tank, defining a confined space above the water level a steam injector having a discharge nozzle submerged in the water: chamber, said nozzle increasing in cross section toward its discharge end and having a region of sudden increasein cross section at its inlet, an air passage leading to the region of sudden increase in cross section and arranged with respect to the steam flow so the steam has an aspirator action on said passage at normal rates of steam flow, water inlets to the nozzle beyond the air passage as regards the direction of steam flow, an air line leading from the interior of the upper part of the tank to the air passage, and a control. valve responsive to the sterilizer temperature for cutting down the flow of steam below the normal flow when the sterilizer comes up to the set temperature to a flow insufiicient to aspirate air.

2. In a sterilizer, a tank having a water chamber in its lower part in which articles to be sterilized are immersed, an overflow maintaining the water level in the chamber, a closure for the tank, defining a confined space above the water level, a steam trap in said overflow, a steam injector aspirator having water and air suction passages submerged below the water level in the chamber and subjected to suction by the aspirator action of the steam jet, and an airline having its inlet to the interior of the tank above the water level and its outlet connected to said air passages.

3. A sterilizer as claimed in claim 2 in which the tank has a pressure tight closure so that when the water is supplied with a detergent, the air injection aids in the creation of suds improving the washing action.

RAYMOND L. JEWELL. GEORGE J. DYCKES.

References Cited in the file of this patent UNITED STATES PATENTS 2,472,011 Graham Mart 194a 

